Hot, dry weather to persist

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In years past, local folks knew it was time for the Hawaii County Fair by the predictable September rains — which some people joked were brought in with the fair’s rides and games.

In years past, local folks knew it was time for the Hawaii County Fair by the predictable September rains — which some people joked were brought in with the fair’s rides and games.

This year though, the hot, dry September that Hilo is experiencing should last at least through the weekend. That means those attending the fair, which opens tonight and runs through Sunday on the grounds of Afook-Chinen Civic Auditorium, should have minimal need for umbrellas and rain gear.

“That’s just the kind of the pattern we’re stuck in,” said Matthew Foster, a National Weather Service meteorologist, Wednesday. “The winds have just been really, really weak. … It’s making it feel more sticky. Our temperatures have been warmer as a result of that.”

Hilo’s high temperatures have been 85 degrees or above every day this month, with record-tying highs on three dates, Sept. 1 at 88 degrees and Sept. 6 at 87 degrees. The high Wednesday reached 89 degrees, tying the record set in 1995.

This month’s rainfall at Hilo International Airport measured a paltry 1.25 inches as of Tuesday, well below the norm of 5.11 inches for the first 16 days of September.

Summer rainfall totals were within normal levels in Hilo. June’s total was 6.57 inches, less than an inch below the average of 7.37 inches and well below the record of 22.7 inches in 1997. July was wetter, at 15.99 inches as opposed to the norm of 10.81 inches, and again far short of the record 28.59 inches that fell in 1982. And 10.81 inches of rain fell in August, almost an inch above the average of 9.85 inches, but not approaching the 26.92 inches recorded in 1991.

Record-low rainfall totals in Hilo for those months were 1.8 inches in June 1985, 3.54 inches in July 1999 and 2.66 inches in August 1971.

Hilo airport’s rainfall for the year as of Wednesday was 81.11 inches, slightly higher than the 79.94 inches average for the year to date. Some upslope Hilo and Puna locations are receiving less rain than usual, and some Hamakua areas have been rainier than normal.

Foster said the usual trade winds, which bring showers and some relief from the heat, have been suppressed by storm systems well north of the islands, such as the remnants of Tropical Storm Fengshen and Tropical Depression 14W.

As for when the trades might return, Foster said, “We’re looking at about Monday, but even then, they’re really not going to be that strong.”

“We’re seeing a bit of a tropical trough south of the islands,” he said. “The Big Island is sitting on the northern fringe of this, and we may get a little bit of added moisture associated with that, probably Saturday night and then again, maybe in the middle of (next) week. It’s kind of hard to say for sure.”

Foster said the moisture could come in the form of scattered showers or possibly just higher humidity. The seven-day forecast lists a 50 percent chance of scattered showers for Saturday night and Sunday, but Foster says NWS forecasters look at two computer models that provide differing predictions as to when trades and trade-wind showers return.

“For the rest of the week and through the weekend, expect the warm days to continue, the really light winds (and) humid conditions,” he said. “One of the models has the trades coming back Monday or Tuesday. The other model is saying it will be later. But (the trades) will be really, really weak.”

Email John Burnett at jburnett@hawaiitribune-herald.com.